Lateral shearing interferometry applied for phase measurement in wavefront coherent synthesis

Wavefront coherent synthesis is widely desired in several important laser systems. Meanwhile, with the help of laser, the following engineering problems can be converted into phase measurement in wavefront coherent synthesis: mirror tiling in large scale astronomical telescopes, and planar diffraction grating tiling in laser pulse compression. The main task for phase measurement in wavefront coherent synthesis is to measure the phase difference between synthesized wavefronts in the form of transmission direction error and piston phase error. In this paper, phase measurement for wavefront coherent synthesis based on lateral shearing interferometer is proposed. No reference beam is necessary so the system is simply structured. Simulations were performed to deduce the quantitative relationship between interferograms and phase errors. A demonstration experiment system of planar mirror tiling was set up. Coherent synthesis of monochromatic wavefront was achieved with transmission direction error of 2″ and piston phase error of 1/20 of the wavelength, with the encircled energy of the far-field diffraction pattern higher than 92.9% of the ideal case.